1. Field of the Invention
The present invention relates to methods for treating materials contaminated with hydrocarbon substances and to compositions for such method. The invention is particularly related to oil contamination in drill cuttings generated from drilling well bores.
2. Description of the Prior Art
Oil contamination of land and water has become a major environmental problem. Many instances have been encountered where ecosystems have been severely damaged due to the accidental spillage of oils or other hydrocarbon compounds.
One area where oil contamination is regularly encountered is in bore-hole drilling systems either on or off shore. In the drilling process, oil contaminated drill cuttings are brought to the surface and collected. The cuttings and other material brought to the surface must be treated to remove the oil contaminants in order to prevent them from seeping into the soil or from being dumped into the water.
In order to address this problem various solutions have been proposed such as, for example, burning the cuttings or washing them with a detergent solution. The first method results in both safety and environmental risks. The second method involves a long process time and, possibly, further contamination risks depending upon the detergent used.
In U.S. Pat. No. 4,242,146, a method for treating oil contaminated drill cuttings from off shore drilling units is taught. In this patent, the contaminated cuttings are contacted with an oil absorbent substance such as clay in order to remove any free oil. The combination of cuttings and absorbent is then returned to the water. This reference does not teach a method of removing the oil contaminant but merely to absorb and free oil from the cuttings.
Various other references teach methods for treating oil spills on water bodies. U.S. Pat. No. 4,925,343 teaches a composition for cleaning oil spills comprising a particulate mixture of wood fiber and hydrophobic cotton lint materials. Similar methods are taught in U.S. Pat. Nos. 4,061,567 and 3,617,564. These references teach the use of synthetic or natural fibers for absorbing hydrocarbon contaminants from water or land.
Although addressing the oil spill these references do not deal with degrading the hydrocarbon contaminant to completely remove the contamination risk.
U.S. Pat. No. 5,395,535 teaches a process for removing hydrocarbon materials from water or land comprising spreading dried plant or vegetable matter over the spill. Cotton gin "trash" or waste is indicated as material for use in this process. The cotton material is spread over the oil spill to absorb and retain the contaminant. The material with absorbed oil is then allowed to ferment wherein bacteria indigenous to the cotton material biodegrade the hydrocarbon contaminants.
U.S. Pat. No. 5,635,392 also teaches a process for treating oil-contaminated material wherein microbial action is used to remove the contaminant. In this reference, a nutrient mixture, along with a microbial inoculum, is taught for addition to hydrocarbon contaminated material to stimulate the growth of the culture. In such manner, the contaminant is removed from the system.
Although the latter two references address the removal of the contaminant, the time taken for such biodegradation may lead to spread of the contamination before the removal is complete.
Thus, a need exists for an efficient process for removing hydrocarbon contamination on water or land and a process that accomplishes such removal while minimizing any leaching of contaminants. Therefore, the present invention seeks to provide a means of:
on-site containment and treatment of drilling residue. PA1 on-site stabilization and immobilization of leachable hydrocarbons using only organic absorbents. PA1 on-site bioremediation of hydrocarbons through natural microbial biodegradation. PA1 1) contacting the material with the treatment composition to immobilize the hydrocarbon contaminant; and, PA1 2) biodegrading the contaminant with the microbial culture.